I completely agree.
The long texts should be at least collapsed somehow showing them only as
tooltips or on some 'Help' or 'Info' buttons press. There is no sense showing
always the long information texts.

Created attachment 123960[details]
Glade file with improved design II
This version moves options to a separate tab - makes the dialog even shorter
and there will be some place for more options. (As I wanted to add there
setting for length of validity of authentication ticket for console helper.)
Which one do you like more?

Keep all options with the tab they relate to. So, version 1 is the better of
the two.
I'd argue that you should use 'h' as the accesskey for Use shadow passwords, and
use 'S' for the SMB checkbox to keep up the pattern of using the first letter
for the other checkboxes.